2008 Joint Meeting of The Geological Society of America, Soil Science Society of America, American Society of Agronomy, Crop Science Society of America, Gulf Coast Association of Geological Societies with the Gulf Coast Section of SEPM

Paper No. 8
Presentation Time: 10:15 AM

Correlation of Eocene-Oligocene Exhumation around the Caribbean: Venezuela, Dominican Republic, Honduras, and Guatemala

SISSON, Virginia, Department of Earth and Atmospheric Sciences, University of Houston, 4800 Calhoun, Houston, TX 77204, AVE LALLEMANT, Hans G., Dept. of Earth Science, Rice Univ, MS-126, Houston, TX 77005-1892 and SORENSEN, Sorena S., Dept of Mineral Sciences, Smithsonian Institution, National Museum of Natural History, PO Box 37012, MRC 119, Washington, DC 20013-7012, j_sisson@netzero.com

We note that there are a significant number of Eocene and Oligocene (49-25 Ma) cooling ages (Ar/Ar amphibole, white mica, and fission track) for both high-pressure subduction complexes and metamorphic basement around the Caribbean. These include the Samana Peninsula HP mélange (Dominican Republic), Cordillera de la Costa HP mélange (Venezuela), Roatan amphibolite (Honduras), as well as the Las Ovejas and El Tambor Formations (Chortís block, Guatemala). Lithological associations for both the Samana Peninsula and Cordillera de la Costa HP mélanges are similar with mafic eclogitic boudins hosted in marble, mica schists, and minor serpentinite. The mafic rocks in both suites have very similar geochemistry. Thus, they may originally be part of the same terrane that is now exposed on both sides of the Caribbean plate.

Other portions of Caribbean subduction complexes and metamorphic basement were metamorphosed and exhumed earlier, ranging from 144 Ma in the Sinua HP mélange (Nicaragua), 116 Ma in the HP mélange (Chortís block, Guatemala), 88-55 Ma in the HP mélange (Maya block, Guatemala), 123-103 in western Cuba, and 85-60 in central and eastern Cuba, 104-64 Ma in the Río San Juan HP complex (Dominican Republic), 67 Ma in Jamaican blueschist, 90-79 Ma in the Villa de Cura group (Venezuela), and 90-80 Ma in Margarita Island (Venezuela). The spread in peak metamorphic and exhumation ages along the Caribbean margin implies a very long-lived subduction zone in some portions and multiple subduction events in other portions. The Eocene-Oligocene exhumation of these HP terranes is probably related to a short-lived change in the relative motion of the Caribbean from strike-slip to north-south collision. This may have caused subduction roll back and triggered the final ascent of these terranes on both the northern and southern margin of the Caribbean.